I/o performance in heterogeneous storage environments

ABSTRACT

An embodiment of the invention may include a method, computer program product, and system for improving I/O performance in a heterogeneous storage environment. The embodiment may include storage devices of different storage device types having different I/O performances. Each of the storage devices is accessible via a SAS interface. The embodiment may include identifying a plurality of storage devices of the heterogeneous storage environment. The embodiment may include creating a table including information about identifiable storage devices and attributes. The embodiment may include separating a block I/O data stream into storage device type classes. The embodiment may include routing I/O requests of corresponding device type classes to their assigned physical lanes using the information included in the table, thereby improving the I/O performance of the heterogeneous storage environment.

BACKGROUND

The invention relates generally to a method for improving I/Operformance of storage systems, and more specifically, to a method forimproving the I/O performance in a heterogeneous storage environment.The invention relates further to a related system, in particular astorage system and a computer program product.

BRIEF SUMMARY

According to one aspect of the present invention, a method for improvingI/O (input/output) performance in a heterogeneous storage environmentmay be provided. The heterogeneous storage environment may includestorage devices of different storage device types having different I/Operformance values. Each of the storage devices may be accessible via aSAS interface. The method may include identifying a plurality of storagedevices of the heterogeneous storage environment, creating a tableincluding information about identifiable storage devices, their storagedevice type and their assigned physical lane, separating a block I/Odata stream into storage device type classes, and routing I/O requestsof corresponding device type classes to their assigned physical lanesusing the information included in the table. Thereby, the I/Operformance of the heterogeneous storage environment is improved.

According to another aspect of the present invention, a related systemfor improving I/O performance in a heterogeneous storage environment maybe provided. The heterogeneous storage environment may include storagedevices of different storage device types having different I/Operformances. Each of the storage devices is accessible via a SASinterface.

BRIEF DESCRIPTION OF THE DRAWINGS

It should be noted that embodiments of the invention are described withreference to different subject-matters. In particular, some embodimentsare described with reference to method type claims, whereas otherembodiments have been described with reference to apparatus type claims.However, a person skilled in the art will gather from the above and thefollowing description that, unless otherwise notified, in addition toany combination of features belonging to one type of subject-matter,also any combination between features relating to differentsubject-matters, in particular, between features of the method typeclaims, and features of the apparatus type claims, is considered to bedisclosed within this document.

The aspects defined above and further aspects of the present invention,are apparent from the examples of embodiments to be describedhereinafter and are explained with reference to the examples ofembodiments, but to which the invention is not limited.

Preferred embodiments of the invention will be described, by way ofexample only, and with reference to the following drawings:

FIG. 1 shows a flow chart of an embodiment of the inventive method forimproving I/O performance in a heterogeneous storage environment;

FIG. 2 shows a block diagram of an embodiment of a storage rack;

FIG. 3 shows a block diagram of an embodiment of a storage controllerwith enclosures for storage devices in a rack system;

FIG. 4 shows a block diagram of an embodiment of elements of a storageenclosure cabinet;

FIG. 5 shows an exemplary layout of the table including data aboard thestorage devices;

FIG. 6 shows an embodiment of the system for improving I/O performancein a heterogeneous storage environment; and

FIG. 7 shows an embodiment of a computing system including the systemfor improving I/O performance in a heterogeneous storage environment.

DETAILED DESCRIPTION

In times of “big data”, enterprise data increase continuously so theyneed to be stored in a controlled and secure way and, in many cases,need to be archived. For this, computer servers are typically connectedto storage systems. Often, the storage systems are connected to theservers via a network, e.g., network attached storage (NAS) system. Thestorage systems typically include a storage controller and a pluralityof storage devices organized in a plurality of arrays of storagedevices. In the past, only hard drives with spinning magnetic disks havebeen used in such storage systems. However, over time, also solid statestorage devices have been developed, like SSDs (solid state drive) orflash memory drives. Often times, these devices may have the samecommunication interface as the traditional hard drives. Commoncommunication interfaces for storage systems include SCSI (smallcomputer system interface), which is a set of American NationalStandards Institute standard electronic interface specification allowinga computer server to communicate with a plurality of differentperipheral hardware systems, including storage devices.

Originally, the SCSI interface was a parallel interface, which, overtime, developed into the Serial Attached SCSI (SAS) interface which canbe seen as today's norm for use in storage systems. Additionally,another technique, namely Serial Advanced Technology Attachment (SATA)may be used to communicate between a computer server and storagedevices.

Typical storage systems include a plurality of storage devices which maybe controlled by a storage controller. The storage controller may be theprimary interface to the network and for the communication with thecomputer server.

Because of the increased usage of SSDs and their exchangeability againsttraditional hard drive storage devices, they may also be used as areplacement for the slower hard drive devices. Thus, heterogeneousstorage environments including hard drive devices mixed with SSDs havebecome a typical use case.

In the context of this description, the following conventions, termsand/or expressions may be used:

The term ‘I/O performance’ may denote the data transfer speed between astorage device like a hard drive device or an SSD and a respectivestorage controller. Because SSDs are much faster as compared to harddrive devices, storage controllers may have a hard time to optimize theoverall performance of a heterogeneous storage environment.

The term ‘heterogeneous storage environment’ may denote a storagesub-system including a plurality of storage devices of different I/Operformance characteristics. The heterogeneous storage environment mayinclude a storage controller and a plurality of storage enclosurecabinets housing the storage devices in arrays. Each of the storageenclosure cabinets may also include a local device controller.

The term ‘storage devices’ may denote a device capable of storing dataof a computing system. Typically, a storage device may be a hardwareperipheral device attached to the computing system. Typical storagedevices may include hard drive devices and solid state drive devices ofvarious types. The storage devices may be housed within a storagecontroller chassis or in expansion units, also denoted as storageenclosure cabinet, connected to a storage controller.

The term ‘storage device type’ may refer to a classification of storagedevices, mainly characterizing its I/O performance. However, also otherattributes may be used to differentiate storage device types, like thesize of the storage device, the used storage technology, the longevityof data in the storage device, and many others.

The term ‘SAS interface’ may denote the abbreviation for Serial AttachedSCSI (small computer system interface).

The term ‘block I/O data stream’ may denote a stream of data between astorage controller and a storage device. Typically, storage devicesstore data in blocks of fixed length. Typical block sizes may be 2 kB or4 kB. However, the proposed method and system is each transparent forthe block size. The block I/O data stream may be used for bothdirections: controller to storage device and storage device tocontroller.

The term ‘assigned physical lane’ may denote a physical electricalconnection between a storage controller and a storage device. Storagedevices may typically be connected to the storage controller in a daisychain manner. The used physical (Phy) SAS links include a set of 4 wiresused as two differential pairs, one pair for transmission (TX) and onepair for a signal reception (RX). A pair of 1 TX and 1 RX is called alane.

The term ‘magnetic hard drive’ (aka HDD) may denote a storage deviceusing at least one rotating (or spinning) magnetic disk to which datamay be written using a read/write head. The same read/write head may beused to read the data from the magnetic hard drive.

The term ‘solid state disk’, abbreviated by SSD, may denote a storagedevice without moving mechanical parts, in particular a spinningmagnetic disk. These SSDs typically use semiconductor devices forstoring the data. Their I/O performance may be much higher than those ofspending magnetic disks—e.g., several 10 times faster. Therefore, andbecause of falling prices for these types of devices, SSDs may often beused as replacements for classical hard drive storage devices.

The term ‘memristor storage’ may denote a storage device based on thetechnology of a non-linear passive two-terminated electric componentrelating electric charge and magnetic flux linkage. Such devices maytoday be implemented in CMOS technology. Each cell of such a memristormay store more than two—in particular “0” and “1”—states by increasingor decreasing a resistor value. Another advantage of memristors is thatthey continue to maintain their statuses without requiring electricalpower. Thus, memristors may be used to build non-volatile random-accessmemory systems.

The term ‘magneto-resistive RAM’—or MRAM—may denote a storage deviceusing my meta-resistive technology. Unlike conventional RAM (randomaccess memory) chip technologies, data in MRAM is not stored as electriccharge or current flows, but by magnetic storage elements. The elementsmay be formed from two ferromagnetic plates, each of which may hold amagnetization, separated by a thin insulating layer. One of the twoplates may be a permanent magnet set to a particular polarity; the otherplate's magnetization may be changed to match that of an external fieldto store memory. This configuration is known as a magnetic tunneljunction and is the simplest structure for an MRAM bit storage. Acomplete storage device may be built from a grid of such “cells”.

The term ‘race track memory’—also domain-wall memory (DWM)—may denote amemory technology also being able to store more than one bit in a singlememory cell. Currently, this technology is still under development andnot yet in commercial use. However, in early 2008, a 3-bit version wassuccessfully demonstrated. If it would become available commercially,racetrack would offer storage density higher than comparable solid-statememory devices like flash memory and similar, also having a higherread/write performance.

The term ‘negotiated link rate’ may denote a used data transfer ratebetween a storage controller and a storage device. The negotiated linkrate may vary from storage device class to storage device class.

The term ‘SAS target negotiated hardware maximum link rate’ may denote amaximum possible communication and data transfer rate between a storagecontroller and a SAS storage device. This maximum link rate may bedependent on the storage device class.

The term ‘SSD device type’ may denote storage device using SSDtechnology. In contrast, the term ‘HDD device type’ may denote a storagedevice using hard drive technology.

The proposed method for improving I/O performance in a heterogeneousstorage environment may offer multiple advantages and technical effects:

The overall performance of heterogeneous storage environments—i.e.,storage systems including a plurality of storage devices of differentstorage classes—may be optimized and increased. This way, the averageaccess times to data in the heterogeneous storage environment may beincreased such that the overall performance of a computer serveraccessing data (read/write) in the heterogeneous storage environment mayalso be increased.

Heterogeneous storage environments, which may develop over time in a wayin which magnetic hard drives may be replaced by SSD storage devices,may adapt themselves to new mixes of hard drives and SSDs. The storagecontroller may reconfigure the grouping of storage devices in order toaddress hard drive storage devices as one group and SSD storage devicesas another group. However, there may also be mixed groups of hard drivedevices and SSD devices. Depending on threshold values, the storagecontroller may be enabled to assign the different devices dynamically toa different group in order to increase the overall I/O performance.

The method may enable the related system to perform self-learningprocedures in order to adapt its behavior over time by monitoringperformance variations in groups of storage devices based on the mixtureof hard drive systems compared to SSD devices and/or HDD.

Furthermore, the disadvantages of the traditional method for managingaccess to storage devices in heterogeneous storage environments may beovercome. Namely, the fact that typically storage devices closer to thestorage controller can be accessed faster than those storage devicesbeing further out in the storage rack. By way of dynamic reconfigurationand re-assignments of storage devices of different classes, the accessspeed—i.e., the I/O performance—to the storage devices may becomeindependent of the position in the daisy-chained storage deviceenclosures. Users may add SSDs to the storage systems dynamically and/orreplacing HDDs against SSDs (or other faster storage devices) withoutshutting down the heterogeneous storage environment—i.e., the respectivestorage controller—and/or repositioning storage devices in theenclosures—i.e., the rack—and re-configuring the controller.

In the following, additional embodiments of the proposed method and therelated system will be described:

According to one preferred embodiment of the method, each of the storagedevice types may be selected out of the group including a magnetic harddrive, a solid state disk, a flash memory, a memristor storage, amagneto-resistive RAM and a race track memory. Additionally, in otherembodiments, an extended list of storage devices may be supported, forexample, a tape drive, a DVD system, and/or other optical or magneticdevice types. Hence, basically there is no limit regarding the devicetypes that may be supported by the proposed method and system. Bysetting the parameters according to the used device types, more or lessany mixture of device types in the heterogeneous storage environment maybe supported.

According to one permissive embodiment of the method, the table mayinclude additionally at least one attribute for each of the identifiedstorage devices. These attributes may be selected out of the groupenclosure ID (ID=identifier value), slot ID, vendor name, SAS initiatorport Type, SAS initiator port ID, SAS initiator physical lane ID, SASenclosure target port ID, SAS enclosure target physical lane ID, SAStarget expander port ID, SAS target expander lane ID, SAS target deviceport ID, SAS target device lane ID, SAS target device negotiated linkrate, SAS target device hardware minimum link rate, SAS target devicehardware maximum link rate, SAS target negotiated hardware maximum linkrate deviation, and a device type. More and other attributes and theirrelated values may be possible. Hence, all parameters that are known ormay be requested from the device may be used as attributes in the table.It may be noted that not all devices types may deliver all attributevalues upon request. In such cases, the respective field may be empty inthe table.

According to one advantageous embodiment, the method, in particular therouting, may include additionally analyzing data blocks stored in an I/Obuffer memory—in particular the I/O buffer of a respective storagecontroller—and assigning, based on the information included in thetable, a device group ID, in particular a so-calledSAS-Phy-Group/Logical-Unit-Number (LUN)—to each of the analyzed datablocks. This may be performed before the respective blocks may betransferred from the I/O buffer memory to the storage device using theassignments.

According to one additionally preferred embodiment of the method, theassigning the device group ID is based on at least one selected out ofthe group including the device type, a SAS target device, a negotiatedlink rate and a SAS target negotiated hardware maximum link rate. Hence,performance parameters play a significant role in the assignment processin order to address devices with comparable performance values together.

According to an additionally advantageous embodiment, the method mayalso include monitoring the I/O performance of each of the devicegroups—i.e., of each device—and re-assigning one of the storage devicesof one storage device group to another device group, in particular toanother device group having another device group ID. Thus, devices maybe moved between differently performing device groups dynamicallywithout a requirement for a reconfiguration of the heterogeneous storagesystem. The system reconfigures itself always in a way to allow for anoptimized performance even if devices may be exchanged, in particularbeing replaced, by higher performing devices (e.g., a hard drive may bereplaced by an SSD device).

According to a further advantageous embodiment of the method, there-assignment may include determining whether a storage device groupperformance of a mixed type device group—in particular HDD (hard drivedevice) and SSD (solid-state device)—may be above a thresholdpercentage—e.g., 80%—of an SSD device type performance and I/O requeststo devices classified as HDD in the mixed type device group may be belowa HDD threshold value, e.g., <50%. This would mean that a typical I/Operformance of such a mixed storage device group is clearly above acalculated mixed I/O performance value because accesses to the SSDs aremore often than to the HDDs. In such a case, a re-assignment of thestorage device group from being classified as HDD class type to an SSDclass type may be performed.

According to an additionally advantageous embodiment of the method, there-assigning may include determining whether a storage device groupperformance of a mixed type device group—in particular HDD and SSD—maybe below the threshold percentage—in particular, e.g., 80%—of an SSDdevice type performance and the I/O performance to devices classified asHDD in the mixed type device group is above a HDD threshold value,e.g., >50%. In such a case, a re-assignment of a storage device groupfrom being classified as SSD class type to an HDD class type may beperformed.

According to an optional embodiment of the method, the re-assigning mayalso include determining whether a trend over a predefined number ofmonitoring cycles of the storage device group performance of the storagedevice group may increase. Thus, not only point in time measurements maybe used for re-assignments of storage device groups to storage classes,but also trends developing over a predefined period of time. This maygive the proposed method and the related system high flexibility inadapting to new storage device types as part of the heterogeneousstorage environment. This may protect made investments in heterogeneousstorage systems allowing storage devices of different storage classes.

Consequently, and according to a further embodiment, the method may alsoinclude monitoring individual storage device performance values overtime, and re-assigning a storage device to another storage device groupusing the individual storage device performance values over time.

In the following, a detailed description of the figures will be given.All instructions in the figures are schematic. Firstly, a block diagramof an embodiment of the inventive method for improving I/O performancein a heterogeneous storage environment is given. Afterwards, furtherembodiments, as well as embodiments of the system for improving I/Operformance in a heterogeneous storage environment, will be described.

FIG. 1 shows a flow chart of an embodiment of the method 100 forimproving I/O performance in a heterogeneous storage environment. Theheterogeneous storage environment includes storage devices of differentstorage device types having different I/O performances. Each of thestorage devices is accessible via a SAS interface. The method 100includes identifying (step 102) a plurality of storage devices of theheterogeneous storage environment. This may be performed by an inquirycommand via the SAS controller using a SAS discover request command andreceiving, e.g., a 62 byte response. This response may identify thedevice class by a plurality of attribute values.

Additionally, the method 100 includes creating (step 104) a table—inparticular a SAS-Phy-Group Target or LUN table—including informationabout identifiable storage devices, their storage device type and theirassigned physical lane, i.e., the target port. Generally, storagedevices of the storage system may be identified.

Furthermore, the method 100 includes separating (step 106) a block I/Odata stream—which may be buffered in the I/O buffer of the storagecontroller before writing the data to the storage device—into storagedevice type classes, and routing (step 108) I/O requests ofcorresponding device type classes to their assigned physical lanes usingthe information included in the table. This way, the overall I/Operformance of the heterogeneous storage environment can be increasedsignificantly.

FIG. 2 shows a block diagram of an embodiment of a storage rack 200 onthe left side of the figure. Symmetrically, on the right side of thefigure, a second storage rack 200 a is shown. Typically, the cabinets,in which the storage controller 202 and enclosure cabinets 204, . . . ,214 are mounted, are 19″ racks or similar. Also shown are examples ofthe connection cables 216 from a socket of one storage device enclosurecabinet 212—here, to another socket 218—here, storage device enclosurecabinet 214. These cables are only shown for the upper half of thefigure of the storage rack shown in solid lines. A skilled person willunderstand that the other connections are done in a respective manner.Only the input and output sockets 218 for the daisy chain connectionsfrom enclosure cabinet to enclosure cabinet carry reference numerals.

The physical connections from the controller to enclosure cabinets aredone via a so-called wide port which provides for high-speed serialconnections. Each storage enclosure can receive data I/O via two lanesfor physical SAS lanes. Other cable material and the respective socketsin the enclosure cabinets are also available.

FIG. 3 shows a block diagram of an embodiment of a storage controller300. The storage controller 300 includes a left storage controllercomponent 302 and a right storage controller component 304. The internalelements of the left and right storage controller component arepractically identical. Therefore, only the internal elements of the leftstorage controller component 302 will be described: a SAS I/O CPU isconnected to a CPU memory 308, a DMA controller 310 and a host I/O cache312. A connection to a server computer is typically done via fiberchannel (FC) connections. For this purpose, the FC host adapter 314 isconnected to the FC host port 316 and a 2^(nd) FC host port 318. Theconnection to the storage devices in the enclosure cabinets is done viathe 1^(st) SAS port 320 and the 2^(nd) SAS port 322. For this, ports areconnected to the SAS I/O CPU 306 via the 1^(st) SAS I/O core 324 and the2^(nd) SAS I/O core 326. Another SAS I/O core 328 is used for aconnection to a corresponding SAS I/O core 328 of the right storagecontroller component 304.

FIG. 4 shows a block diagram of an embodiment of a storage enclosurecabinet 402. The storage enclosure cabinet 402 includes a 1^(st) SASexpander 404 and a 2^(nd) SAS expander 406. Each of the SAS expandersincludes a local controller to access the physical storage devices 408to 410. Typically, up to 24 storage devices may be installed perenclosure cabinet. As can be seen, two SAS lanes to the storage devicemay be installed, from the 1^(st) SAS expander 404 to the respectivestorage device as well as from the 2^(nd) SAS expander 406. Typicalenclosure cabinets 402 may house, e.g., 24 physical storage devices 408,410.

FIG. 5 shows an exemplary layout of the table 500 including the assignedphysical lane (LUN) logical unit number, an ID of the storage device(UID) and their storage device type (Type). Additional other attributesof each device may also be included as additional column into the table,as discussed above.

In the following, a more comprehensive explanation is given in order tounderstand the full value of the proposed solution: firstly, it may benoted that the physical layout of existing storage controllers may beused for the proposed approach. In an alternative solution, additionalSAS lanes may have been installed in order to be able to separate theI/O communication by different speeds of the different storage deviceclasses. A special SAS I/O optimizer module may have also beenimplemented which may include a SAS network switch capability to manageSAS ports for storage device groups/zones, to separate different latencydata streams.

An additional software module may be required to match the communicationstreams.

The proposed solution may be implemented using software only. However,specific components, modules and/or units of the proposed solution maybe implemented in hardware. This may have performance advantages and mayaddress security issues as well.

Firstly, a typical scenario is provided describing how heterogeneousstorage environments may develop over time: at a time T0, customersstart with a storage system including only HDDs. However, physicalstorage devices of different vendors may be used; thus, already at thispoint in time, the storage system may be described as heterogeneous.

At another point in time T1, additional capacity is needed andadditional HDDs are added. This increases the total storage capacity. Atagain another point in time T2, new storage technology becomescommercially available, e.g., SSDs. At a point in time T3, the user ofthe heterogeneous storage environment requires additional storagecapacity and adds storage devices using the new storage technology, inparticular SSDs. At a time T4, available storage systems may bereconstructed because of the shift to the higher percentage of the newstorage technology. Alternatively, the available storage systems may beconsolidated to fewer storage systems because capacities of individualstorage devices may have increased over time. However also old HDDs maybe reused in the consolidated systems.

At again another point in time T5, again newer storage technology mayhave become available, e.g., even faster SSDs or those with highercapacity have become available. In any case, today typical storageenvironments are operated 24 hours/7 days a week without interruptionand the capacity growth of the storage systems should be implementedwithout any downtime. Therefore, typically additional storage enclosurecabinets—or expansion units—are simply added to the storage systems. Theusers do not want to power down the storage system and physicallyreconfigure the storage devices already installed in the expansionunits.

Now, a sequence of operational steps of the proposed method and therelated system will be described:

Step 1. A device type SAS-Phy-Group-target/LUN table is created andspecific devices are added to the table (see above). The table ofattached storage devices is formed using a command like SAS discover,SAS inquiry and SAS response from a SAS enclosure service (SES). Thetable may be created in the SAS controller flash memory of the SAScontroller that controls the SAS initiator ports (compare 320, 322) tothe attached target storage device. Over and above the attributes shownin the table according to FIG. 5, many more attribute values may becollected during this process like those already mentioned above:enclosure#, slot#, vendor name, device type, SAS initiator port type,SAS initiator port ID, SAS initiator physical lane ID, SAS EnclosureTarget Port ID, SAS Enclosure Target Physical Lane ID, SAS targetexpander port ID, SAS target expander lane ID, SAS target device portID, SAS target device lane ID, SAS target device negotiated link rate,SAS target device hardware minimum link rate, SAS target device hardwaremaximum link rate, SAS target negotiated hardware maximum link ratedeviation. Generally, the table may be expanded for usage of otheradditional attributes.

Step 2. A software module that analyses the data blocks stored from thehost into the storage systems I/O-buffer memory may be used. Thesoftware module is cyclically releasing one or more parallelprocess-threads seeking through the I/O-buffer memory and analyzing eachdata block to which target/LUN ID it should be stored to and flags theblock to a SAS-Phy-Group. One or more SAS-Phy-Groups may be assigned.The SAS-Phy-Group assignment may be done based on the informationprovided in the table described in the context of FIG. 5 under the firststep.

Step 3. The function to read the SAS-Phy-Group-Flag of the data-block inthe I/O buffer memory of the storage controller is implemented. In thehere described example, only 2 SAS-Phy-Groups are explained.

Step 4. If a data block is flagged to be transferred to a target and LUNheld by a SSD storage device, the data blocks are transferred from thestorage system I/O-buffer memory via SAS-Phy-Group assigned to SSDdevice.

Step 5. If the data-block is flagged to be transferred to a target andLUN hold by a HDD storage device, the data blocks are transferred fromthe storage system I/O-buffer memory via the SAS-Phy-Group assigned toHDD device.

Step 6. Another software module is added to monitor the SAS-I/Operformance on each device type as highest possible level. With theI/O-Performance of the different device types used in a storage systemmonitored, the software module dynamically changes the SAS-Phy-Groupassignment in the table.

Step 6a. As an example: In the storage system, one may have 2 SAS portseach operating 4 physical SAS-Lanes. The invented software module isreading I/O history learning table, described in step 7 below, atinitial start. If the I/O historical learning table is empty, like incase of a first time initial start of the storage system, the disk typeSSD has 50% of the Physical SAS lanes assigned in SAS-Port A and 50% ofthe Physical SAS lanes assigned in SAS-Port B. The other 50% of the SASlanes are then assigned to SAS-Phy-Group for disk type HDD.

Step 6b. Now, if the added software SAS lane monitor is reaching thethreshold of higher than, e.g., 80% on the I/O in SAS-Phy-Group to theDisk Type SSD, with trend increasing, AND the threshold for I/O inSAS-Phy-Group to the Disk-Type HDD is lower than, e.g., 50%, thesoftware module removes a physical SAS lane from the SAS-Phy-Group ofDisk-Type HDD and assigns it to the SAS-Phy-Group for Disk-Type SSD.

Step 6c. In the opposite way, if the added software SAS lane monitor isreaching the threshold of higher than 80% on the I/O in SAS-Phy-Group tothe Disk Type HDD, with trend increasing, AND the threshold for I/O inSAS-Phy-Group to the Disk-Type SSD is lower than 50%, the softwaremodule removes a physical SAS Lane from the SAS-Phy-Group of Disk-TypeSSD and assigns it to the SAS-Phy-Group for Disk-Type HDD.

Step 6d. In the case of the added software SAS lane monitor isdetermining a threshold of higher than 80% on the I/O in bothSAS-Phy-Groups to both used Disk-Types, HDD AND SSD, then no changes canbe made in the first step. In this case, the I/O transport will bemanaged based on the amount of I/O-buffer memory used by the dataflagged for each SAS-Phy-Group. Then, the monitor will thread anotherprogram to inform the added software module analyzing the data blocksstored from the host into the storage systems I/O-buffer memory tothrottle (i.e., delay) the I/O performance as possible and initiate analert of “physical SAS Bandwith limits are reached” to the operator.

Step 7. Another function of the SAS-I/O performance software monitor,described in step 6 before, is the historical recording of the time whena host is operating I/O to/from a storage type into a database table,I/O historical learning. The function is recording the time stamp, thenumber of blocks transferred, the target/LUN and device type to whichthe I/O was performed and the time stamp of when the I/O operationfinished. Based on this data the function analyzes the I/O pattern andtiming and provides the necessary amount of SAS lanes required for eachdisk type and SAS-Phy-Group of lanes into a planning table. The planningtable is accessed by the added SAS-I/O performance software monitorfrequently during operation and after a boot of the storage system toprovide the initial optimal physical SAS lane assignment into the SASlane groups for the different used device types, as described in Step6a.

FIG. 6 shows an embodiment of the system 600 for improving I/Operformance in a heterogeneous storage environment in a more condensedway. In the system 600, the heterogeneous storage environment includesstorage devices of different storage device types having different I/Operformances. Each of the storage devices is accessible via a SASinterface. The system includes an identification unit 602 adapted foridentifying a plurality of storage devices of the heterogeneous storageenvironment and a creation module 604 adapted for creating a tableincluding information about identifiable storage devices, their storagedevice type and their assigned physical lane.

Furthermore, the system 600 includes a separation unit 606 adapted forseparating a block I/O data stream into storage device type classes, anda routing controller 608 adapted for routing I/O requests ofcorresponding device type classes to their assigned physical lanes usingthe information included in the table, thereby improving the I/Operformance of the heterogeneous storage environment.

Embodiments of the invention may be implemented together with virtuallyany type of computer, regardless of the platform being suitable forstoring and/or executing program code.

FIG. 7 shows, as an example, a computing system 700 suitable forexecuting program code related to the proposed method. The storagecontroller (compare FIG. 3 and the related explanations) may be seen asa computing system 700 itself because it may include all necessarycomponents.

The computing system 700 is only one example of a suitable computersystem and is not intended to suggest any limitation as to the scope ofuse or functionality of embodiments of the invention described herein.Regardless, computer system 700 is capable of being implemented and/orperforming any of the functionality set forth hereinabove. In thecomputer system 700, there are components, which are operational withnumerous other general purpose or special purpose computing systemenvironments or configurations. Examples of well-known computingsystems, environments, and/or configurations that may be suitable foruse with computer system/server 700 include, but are not limited to,personal computer systems, server computer systems, thin clients, thickclients, hand-held or laptop devices, multiprocessor systems,microprocessor-based systems, set top boxes, programmable consumerelectronics, network PCs, minicomputer systems, mainframe computersystems, and distributed cloud computing environments that include anyof the above systems or devices, and the like. Computer system/server700 may be described in the general context of computersystem-executable instructions, such as program modules, being executedby a computer system 700. Generally, program modules may includeroutines, programs, objects, components, logic, data structures, and soon that perform particular tasks or implement particular abstract datatypes. Computer system/server 700 may be practiced in distributed cloudcomputing environments where tasks are performed by remote processingdevices that are linked through a communications network. In adistributed cloud computing environment, program modules may be locatedin both local and remote computer system storage media including memorystorage devices.

As shown in the figure, computer system/server 700 is shown in the formof a general-purpose computing device. The components of computersystem/server 700 may include, but are not limited to, one or moreprocessors or processing units 702, a system memory 704, and a bus 706that links with various system components including system memory 704 tothe processor 702. Bus 706 represents one or more of any of severaltypes of bus structures, including a memory bus or memory controller, aperipheral bus, an accelerated graphics port, and a processor or localbus using any of a variety of bus architectures. By way of example, andnot limitation, such architectures include Industry StandardArchitecture (ISA) bus, Micro Channel Architecture (MCA) bus, EnhancedISA (EISA) bus, Video Electronics Standards Association (VESA) localbus, and Peripheral Component Interconnects (PCI) bus. Computersystem/server 700 typically includes a variety of computer systemreadable media. Such media may be any available media that is accessibleby computer system/server 700, and it includes both, volatile andnon-volatile media, removable and non-removable media.

The system memory 704 may include computer system readable media in theform of volatile memory, such as random access memory (RAM) 708 and/orcache memory 710. Computer system/server 700 may further include otherremovable/non-removable, volatile/non-volatile computer system storagemedia. By way of example only, storage system 712 may be provided forreading from and writing to a non-removable, non-volatile magnetic media(not shown and typically called a ‘hard drive’). Although not shown, amagnetic disk drive for reading from and writing to a removable,non-volatile magnetic disk (e.g., a ‘floppy disk’), and an optical diskdrive for reading from or writing to a removable, non-volatile opticaldisk such as a CD-ROM, DVD-ROM or other optical media may be provided.In such instances, each can be connected to bus 706 by one or more datamedia interfaces. As will be further depicted and described below,memory 704 may include at least one program product having a set (e.g.,at least one) of program modules that are configured to carry out thefunctions of embodiments of the invention.

The program/utility, having a set (at least one) of program modules 716,may be stored in memory 704 by way of example, and not limitation, aswell as an operating system, one or more application programs, otherprogram modules, and program data. Each of the operating system, one ormore application programs, other program modules, and program data orsome combination thereof, may include an implementation of a networkingenvironment. Program modules 716 generally carry out the functionsand/or methodologies of embodiments of the invention as describedherein.

The computer system/server 700 may also communicate with one or moreexternal devices 718 such as a keyboard, a pointing device, a display720, etc.; one or more devices that enable a user to interact withcomputer system/server 700; and/or any devices (e.g., network card,modem, etc.) that enable computer system/server 700 to communicate withone or more other computing devices. Such communication can occur viaInput/Output (I/O) interfaces 714. Still yet, computer system/server 700may communicate with one or more networks such as a local area network(LAN), a general wide area network (WAN), and/or a public network (e.g.,the Internet) via network adapter 722. As depicted, network adapter 722may communicate with the other components of computer system/server 700via bus 706. It should be understood that although not shown, otherhardware and/or software components could be used in conjunction withcomputer system/server 700. Examples, include, but are not limited to:microcode, device drivers, redundant processing units, external diskdrive arrays, RAID systems, tape drives, and data archival storagesystems, etc.

Additionally, the system 600 for improving I/O performance in aheterogeneous storage environment may be attached to the bus system 706.

The descriptions of the various embodiments of the present inventionhave been presented for purposes of illustration, but are not intendedto be exhaustive or limited to the embodiments disclosed. Manymodifications and variations will be apparent to those of ordinaryskills in the art without departing from the scope and spirit of thedescribed embodiments. The terminology used herein was chosen to bestexplain the principles of the embodiments, the practical application ortechnical improvement over technologies found in the marketplace, or toenable others of ordinary skills in the art to understand theembodiments disclosed herein.

The present invention may be embodied as a system, a method, and/or acomputer program product. The computer program product may include acomputer readable storage medium (or media) having computer readableprogram instructions thereon for causing a processor to carry outaspects of the present invention.

The medium may be an electronic, magnetic, optical, electromagnetic,infrared or a semi-conductor system for a propagation medium. Examplesof a computer-readable medium may include a semi-conductor or solidstate memory, magnetic tape, a removable computer diskette, a randomaccess memory (RAM), a read-only memory (ROM), a rigid magnetic disk andan optical disk. Current examples of optical disks include compactdisk-read only memory (CD-ROM), compact disk-read/write (CD-R/W), DVDand Blu-Ray-Disk.

The computer readable storage medium can be a tangible device that canretain and store instructions for use by an instruction executiondevice. The computer readable storage medium may be, for example, but isnot limited to, an electronic storage device, a magnetic storage device,an optical storage device, an electromagnetic storage device, asemiconductor storage device, or any suitable combination of theforegoing. A non-exhaustive list of more specific examples of thecomputer readable storage medium includes the following: a portablecomputer diskette, a hard disk, a random access memory (RAM), aread-only memory (ROM), an erasable programmable read-only memory (EPROMor Flash memory), a static random access memory (SRAM), a portablecompact disc read-only memory (CD-ROM), a digital versatile disk (DVD),a memory stick, a floppy disk, a mechanically encoded device such aspunch-cards or raised structures in a groove having instructionsrecorded thereon, and any suitable combination of the foregoing. Acomputer readable storage medium, as used herein, is not to be construedas being transitory signals per se, such as radio waves or other freelypropagating electromagnetic waves, electromagnetic waves propagatingthrough a waveguide or other transmission media (e.g., light pulsespassing through a fiber-optic cable), or electrical signals transmittedthrough a wire.

Computer readable program instructions described herein can bedownloaded to respective computing/processing devices from a computerreadable storage medium or to an external computer or external storagedevice via a network, for example, the Internet, a local area network, awide area network and/or a wireless network. The network may includecopper transmission cables, optical transmission fibers, wirelesstransmission, routers, firewalls, switches, gateway computers and/oredge servers. A network adapter card or network interface in eachcomputing/processing device receives computer readable programinstructions from the network and forwards the computer readable programinstructions for storage in a computer readable storage medium withinthe respective computing/processing device.

Computer readable program instructions for carrying out operations ofthe present invention may be assembler instructions,instruction-set-architecture (ISA) instructions, machine instructions,machine dependent instructions, microcode, firmware instructions,state-setting data, or either source code or object code written in anycombination of one or more programming languages, including anobject-oriented programming language such as Smalltalk, C++ or the like,and conventional procedural programming languages, such as the “C”programming language or similar programming languages. The computerreadable program instructions may execute entirely on the user'scomputer, partly on the user's computer as a stand-alone softwarepackage, partly on the user's computer and partly on a remote computeror entirely on the remote computer or server. In the latter scenario,the remote computer may be connected to the user's computer through anytype of network, including a local area network (LAN) or a wide areanetwork (WAN), or the connection may be made to an external computer(for example, through the Internet using an Internet Service Provider).In some embodiments, electronic circuitry including, for example,programmable logic circuitry, field-programmable gate arrays (FPGA), orprogrammable logic arrays (PLA) may execute the computer readableprogram instructions by utilizing state information of the computerreadable program instructions to personalize the electronic circuitry,in order to perform aspects of the present invention.

Aspects of the present invention are described herein with reference toflowchart illustrations and/or block diagrams of methods, apparatus(systems), and computer program products according to embodiments of theinvention. It will be understood that each block of the flowchartillustrations and/or block diagrams, and combinations of blocks in theflowchart illustrations and/or block diagrams, can be implemented bycomputer readable program instructions.

These computer readable program instructions may be provided to aprocessor of a general purpose computer, special purpose computer, orother programmable data processing apparatus to produce a machine, suchthat the instructions, which execute via the processor of the computeror other programmable data processing apparatus, create means forimplementing the functions/acts specified in the flowchart and/or blockdiagram block or blocks. These computer readable program instructionsmay also be stored in a computer readable storage medium that can directa computer, a programmable data processing apparatus', and/or otherdevices to function in a particular manner, such that the computerreadable storage medium having instructions stored therein includes anarticle of manufacture including instructions which implement aspects ofthe function/act specified in the flowchart and/or block diagram blockor blocks.

The computer readable program instructions may also be loaded onto acomputer, other programmable data processing apparatus', or anotherdevice to cause a series of operational steps to be performed on thecomputer, other programmable apparatus or other device to produce acomputer implemented process, such that the instructions which executeon the computer, other programmable apparatus', or another deviceimplement the functions/acts specified in the flowchart and/or blockdiagram block or blocks.

The flowcharts and/or block diagrams in the Figures illustrate thearchitecture, functionality, and operation of possible implementationsof systems, methods, and computer program products according to variousembodiments of the present invention. In this regard, each block in theflowchart or block diagrams may represent a module, segment, or portionof instructions, which includes one or more executable instructions forimplementing the specified logical function(s). In some alternativeimplementations, the functions noted in the block may occur out of theorder noted in the figures. For example, two blocks shown in successionmay, in fact, be executed substantially concurrently, or the blocks maysometimes be executed in the reverse order, depending upon thefunctionality involved. It will also be noted that each block of theblock diagrams and/or flowchart illustration, and combinations of blocksin the block diagrams and/or flowchart illustration, can be implementedby special purpose hardware-based systems that perform the specifiedfunctions or act or carry out combinations of special purpose hardwareand computer instructions.

The terminology used herein is for the purpose of describing particularembodiments only and is not intended to limit the invention. As usedherein, the singular forms “a”, “an” and “the” are intended to includethe plural forms as well, unless the context clearly indicatesotherwise. It will further be understood that the terms “comprises”and/or “comprising,” when used in this specification, specify thepresence of stated features, integers, steps, operations, elements,and/or components, but do not preclude the presence or addition of oneor more other features, integers, steps, operations, elements,components, and/or groups thereof.

The corresponding structures, materials, acts, and equivalents of allmeans or steps plus function elements in the claims below are intendedto include any structure, material, or act for performing the functionin combination with other claimed elements, as specifically claimed. Thedescription of the present invention has been presented for purposes ofillustration and description, but is not intended to be exhaustive orlimited to the invention in the form disclosed. Many modifications andvariations will be apparent to those of ordinary skills in the artwithout departing from the scope and spirit of the invention. Theembodiments are chosen and described in order to best explain theprinciples of the invention and the practical application, and to enableothers of ordinary skills in the art to understand the invention forvarious embodiments with various modifications, as are suited to theparticular use contemplated.

The descriptions of the various embodiments of the present inventionhave been presented for purposes of illustration, but are not intendedto be exhaustive or limited to the embodiments disclosed. Theterminology used herein was chosen to explain the principles of the oneor more embodiments, the practical application or technical improvementover technologies found in the marketplace, or to enable others ofordinary skill in the art to understand the embodiments. Variousmodifications, additions, substitutions, and the like will be apparentto those of ordinary skill in the art without departing from the scopeand spirit of the invention, as defined in the following claims.

1. A method for improving I/O performance in a heterogeneous storageenvironment, wherein the heterogeneous storage environment comprisesstorage devices of different storage device types having different I/Operformances, and wherein each of the storage devices is accessible viaa SAS interface, the method comprising: identifying a plurality ofstorage devices of the heterogeneous storage environment; creating atable comprising information about identifiable storage devices, theirstorage device type and their assigned physical lane; separating a blockI/O data stream, stored in an I/O buffer memory, according to storagedevice type; and routing I/O requests of corresponding storage devicetype to their assigned physical lanes using the information comprised inthe table, thereby improving the I/O performance of the heterogeneousstorage environment.
 2. The method of claim 1, wherein each of thestorage device types is selected from the group consisting of a magnetichard drive, a solid state disk, a flash memory, a memristor storage, amagneto-resistive RAM, and a race track memory.
 3. The method of claim1, wherein the table comprises additionally at least one attribute foreach of the identified storage devices selected from the groupconsisting of enclosure ID, slot ID, vendor name, SAS initiator portType, SAS initiator port ID, SAS initiator physical lane ID, SASenclosure target port ID, SAS enclosure target physical lane ID, SAStarget expander port ID, SAS target expander lane ID, SAS target deviceport ID, SAS target device lane ID, SAS target device negotiated linkrate, SAS target device hardware minimum link rate, SAS target devicehardware maximum link rate, SAS target negotiated hardware maximum linkrate deviation, and a device type.
 4. The method of claim 1, furthercomprising: analyzing data blocks stored in the I/O buffer memory; andassigning, based on the information comprised in the table, a devicegroup ID to each of the analyzed data blocks.
 5. The method of claim 4,wherein assigning the device group ID is based on at least one selectedfrom the group consisting of the storage device type, a SAS targetdevice, a negotiated link rate, and a SAS target negotiated hardwaremaximum link rate.
 6. The method of claim 1, further comprising:monitoring the I/O performance of each of the storage devices; andre-assigning one of the storage devices of one storage device group toanother storage device group.
 7. The method of claim 6, wherein there-assigning comprises determining whether a storage device groupperformance of a mixed type device group is above a threshold percentageof an SSD device type performance and I/O requests to devices classifiedas HDD in the mixed type device group is below a HDD threshold value. 8.The method of claim 6, wherein the re-assigning comprises determiningwhether a storage device group performance of a mixed type device groupis below the threshold percentage of an SSD device type performance andI/O requests to devices classified as HDD in the mixed type device groupis above a HDD threshold value.
 9. The method of claim 6, wherein there-assigning comprises determining whether a trend over a predefinednumber of monitoring cycles of the storage device group performance ofthe storage device group increases.
 10. The method of claim 1, furthercomprising: monitoring individual storage device performance values overtime; and re-assigning a storage device to another storage device groupusing the individual storage device performance values over time.
 11. Acomputer system for improving I/O performance in a heterogeneous storageenvironment, wherein the heterogeneous storage environment comprisesstorage devices of different storage device types having different I/Operformances, and wherein each of the storage devices is accessible viaa SAS interface, the computer system comprising: one or more processors,one or more computer-readable memories, one or more computer-readabletangible storage devices, and program instructions stored on at leastone of the one or more storage devices for execution by at least of theone or more processors via at least one of the one or more memories, theprogram instructions comprising; program instructions to identify aplurality of storage devices of the heterogeneous storage environment;program instructions to create a table comprising information aboutidentifiable storage devices, their storage device type and theirassigned physical lane; program instructions to separate a block I/Odata stream, stored in an I/O buffer memory, according to storage devicetype; and program instructions to route I/O requests of correspondingstorage device type to their assigned physical lanes using theinformation comprised in the table, thereby improving the I/Operformance of the heterogeneous storage environment.
 12. The computersystem of claim 11, wherein each of the storage device types is selectedfrom the group consisting of a magnetic hard drive, a solid state disk,a flash memory, a memristor storage, a magneto-resistive RAM, and a racetrack memory.
 13. The computer system of claim 11, wherein the tablecomprises additionally at least one attribute for each of the identifiedstorage devices selected from the group consisting of enclosure ID, slotID, vendor name, SAS initiator port Type, SAS initiator port ID, SASinitiator physical lane ID, SAS enclosure target port ID, SAS enclosuretarget physical lane ID, SAS target expander port ID, SAS targetexpander lane ID, SAS target device port ID, SAS target device lane ID,SAS target device negotiated link rate, SAS target device hardwareminimum link rate, SAS target device hardware maximum link rate, SAStarget negotiated hardware maximum link rate deviation, and a devicetype.
 14. The computer system of claim 11, further comprising: programinstructions to analyze data blocks stored in the I/O buffer memory; andprogram instructions to assign, based on the information comprised inthe table, a device group ID to each of the analyzed data blocks. 15.The computer system of claim 14, wherein assigning the device group IDis based on at least one selected from the group consisting of thestorage device type, a SAS target device, a negotiated link rate, and aSAS target negotiated hardware maximum link rate.
 16. The computersystem of claim 11, further comprising: program instructions to monitorthe I/O performance of each of the storage devices; and programinstructions to re-assign one of the storage devices of one storagedevice group to another storage device group.
 17. The computer system ofclaim 16, wherein the re-assign comprises program instructions todetermine whether a storage device group performance of a mixed typedevice group is above a threshold percentage of an SSD device typeperformance and I/O requests to devices classified as HDD in the mixedtype device group is below a HDD threshold value.
 18. The computersystem of claim 16, wherein the re-assign comprises program instructionsto determine whether a storage device group performance of a mixed typedevice group is below the threshold percentage of an SSD device typeperformance and I/O requests to devices classified as HDD in the mixedtype device group is above a HDD threshold value.
 19. The computersystem of claim 11, further comprising: program instructions to monitorindividual storage device performance values over time, and programinstructions to re-assign a storage device to another storage devicegroup using the individual storage device performance values over time.20. A computer program product for improving I/O performance in aheterogeneous storage environment wherein the heterogeneous storageenvironment comprises storage devices of different storage device typeshaving different I/O performances, and wherein each of the storagedevices is accessible via a SAS interface, the computer program productcomprising: one or more computer-readable storage devices and programinstructions stored on at least one of the one or more tangible storagedevices, the program instructions comprising: program instructions toidentify a plurality of storage devices of the heterogeneous storageenvironment; program instructions to create a table comprisinginformation about identifiable storage devices, their storage devicetype and their assigned physical lane; program instructions to separatea block I/O data stream, stored in an I/O buffer memory,according tostorage device type classes; and program instructions to route I/Orequests of corresponding storage device type to their assigned physicallanes using the information comprised in the table, thereby improvingthe I/O performance of the heterogeneous storage environment.